Oxidation of organoboron compounds



United States Patent Ofiice 3,061,626 Patented Oct. 30, 1962 3,061,626QXlDATlGN F ORGANOBORON COMPOUNDS Tillmon H. Pearson and KennethPresswood, Baton Rouge, La., assignors to Ethyl Corporation, New York,N.Y., a corporation of Delaware No Drawing. Filed Mar. 30, 1960, Ser.No. 18,494 9 Claims. (Cl. 260-462) The present invention is concernedwith a method for the controlled oxidation of organoboron compounds,particularly to form boric acid esters, alcohols, or phenols directly.

It has long been known that organoboron compounds, for example,t-rialkylboraues, can be oxidized by various techniques to form thecorresponding boron esters which in turn can be hydrolyzed to result inthe alcohols. For example, it is known that the trialkylboranes can bereacted with various peroxides, such as hydrogen peroxide, in thepresence of bases to produce the esters. These procedures are of limitedutility because of the cost involved and consequently they have not beenemployed on a commercial scale. Accordingly, there is a need for a moreeconomical method for oxidizing organoborane compounds and others haveattempted with little or no success to fulfill this need.

In order to obviate the above disadvantages of the prior art methods foroxidizing organoboron compounds, there have been attempts to accomplishthe oxidation by the controlled reaction of the organoboron compoundswith air or oxygen. This, of course, is highly desirable because of thehigh economies possible using either air or oxygen. However, there areinherent disadvantages in the known prior art techniques of controlledoxidation either with air or oxygen. For example, when moist air isemployed for oxidizing a trialkylborane, only one alkyl group isoxidized resulting in only one mole of alcohol after hydrolysis per moleof trialkyl borane. The employment of dry air on the other hand resultsin the oxidation of two of the alkyl groups which is, of course, moreadvantageous than the moist air technique but more costly in that theair must be dried. In only one instance is there any report of oxidizingthe so-called last alkyl group with air or oxygen and this has been whenemploying dry air. However, the amount of oxidation of the last carbonto boron linkage was very slow requiring many days in order to obtainappreciable controlled oxidation. Further, the process requiresstringent control in order to eliminate the presence of any water sincewhen the same reaction Was attempted using moist air, no oxidation wasobtained even after maintaining the system under pressure for 18 months.The literature is abundant in pointing out the problem that with air oroxygen it has been impossible to oxidize more than two alkyl groups andif there were only one alkyl group present in the initial organoboranereactant, e.g. RL-(OR) there is no convenient or practical techniqueknown for oxidizing this so-called last carbon to boron linkage. We havemade many attempts employing the presently known techniques to effect acomplete controlled oxidation of compounds having carbon to boronlinkages with air or oxygen and consistent with the prior art were notable to achieve the controlled oxidation of the last carbon to boronlinkage even in dry air. Therefore, it is highly desirable to providethe art with a method for oxidizing organoboranes by which all boron tocarbon linkages are reacted in order to effect complete oxidation to ROBmoieties and result in the most efficient utilization of thisintermediate for forming boron esters or ultimately the more desirablealcohol product.

Accordingly, an object of this invention is to provide a novel processfor the controlled oxidation of organoboron compounds, that is,compounds having carbon linked Cir directly to boron. Another object ofthis invention is to provide a more efficient and economical method forthe controlled oxidation of the organoboron compounds in higher yieldand purity. A particular object is to provide a method whereby allcarbon to boron linkages in an organoboron compound are selectivelyoxidized to ROB moieties. A still more specific object is to provide ameth od whereby in addition to oxidizing all the carbon to boronlinkages in an organoboron compound, an alcohol is directly produced inthe reaction mixture in high yield and readily recoverable therefrom.

The above and other objects of this invention are accomplished byreacting an organoboron compound having at least one carbon to boronlinkage with oxygen in the presence of an amine or ammonia to efiectcontrolled oxidation of the carbon to boron linkages. Thetrialkylboranes in which the alkyl groups are straight chain hydrocarbongroups having up to about 40 carbon atoms comprise preferred organoboroncompounds. Likewise, the tertiary amines, particularly the trialkylamines, having up to about 8 carbon atoms in each alkyl group have beenfound most advantageous. While the temperature and pressure at which thereaction is conducted are subject to considerable latitude, so long asthe reaction is carried out in a temperature insufficient to causeignition or combustion of the organoboron compound, best results areobtained at a temperature of 0 to C. with the pressure above atmosphericbut below 1,000 pounds per square inch (p.s.i.). Thus, one embodiment ofthis invention comprises reacting a trialkylborane with oxy gen, whetheressentially pure or in air, at a temperature between about 0 to 150 C.,a pressure above atmospheric but below about 1,000 psi. in the presenceof a minor amount of a tertiary amine, particularly a trialkyl amine.The direct product of the process is a boron compound having one or moreester linkages, i.e., ROB, formed by the controlled reaction of theoxygen with the carbon to'boron linkage(s). However, an alternative andpreferable embodiment of the invention is to conduct the above-describedreaction in the further presence of water. By so doing, an immediate anddirect hydrolysis is accomplished so that rather than obtaining theester, the corresponding alcohol is directly produced which is readilyrecovered by conventional techniques, usually being immiscible in thereaction mixture. Thus, a particularly preferred embodiment of thisinvention comprises the reaction of a t-rialkylborane, especially one inwhich each alkyl group contains up to about 40 carbon atoms, with oxygenor air at the aforementioned temperature and pressure conditions in thepresence of at least a minor amount of a tertiary amine, particularly atrialkyl amine, and in the further presence of at least sufficient waterto hydrolyze the ester moieties (ROB), in the reaction mixture. Theseand other embodiments of the invention will be brought forth in greaterdetail in the discussion which follows.

The process of this invention is of particular advantage in that thecontrolled oxidation of organoboron compounds is accomplished in aneflicient and practical manner. A specific advantage of the process isthe fact that complete oxidation takes place whereby all carbon to boronlinkages are oxidized. Until the present invention, no convenient,practical and economical procedure for the oxidation of the so-ca-lledlast carbon-boron linkage in an organoboron compound has been possible.

Indeed, so far as we are aware, this has never been accomplished by anair or oxygen oxidation method in a practical manner. Additionally, theprocess provides a method whereby moist air or oxygen can be used tooxidize the so-called last carbon to boron linkage. Still further, thepresent process is of advantage in that when conducting the reaction inthe further presence of water,

the alcohols are directly produced in a manner readily adaptable tocontinuous operation. Still further advantages will be evident as thediscussion proceeds.

I The process involves the employment of organoboron compounds,particularly hydrocarbon boron compounds, which have at least one carbonto boron linkage. The carbon to boron linkage is the primary requisiteof this reactant since this linkage is what is oxidized and desired tobe reacted in the process. The remaining valences of the boron can beother ligands including those which are reactive to oxygen provided thatthey do not destroy the reactivity of the oxygen with the carbon toboron linkages. Thus, such other ligands can be, for example, molitiessuch as the hydrocarbon radicals, alcohol residues (OR), hydrogen,halogens, hydroxyl groups, inorganic acid anions, organic acid anions,particularly of the alkanoic acids, salt structures, (-OM), particularlywhere M is an metal, and the like. It is preferable, however, that suchother ligands can be selected from thesame or different hydrocarbonradicals, and hydroxyl groups. Thus, included among the organoboronreactants employed in the process of this invention are thetrialkylboranes as, for example, trimethylborane, triethylborane,tributylborane, tri-S-methylbutylborane, tri- A-methylpentylborane,trihexylborane, trioctylborane, tridecylborane, triundecylborane,tridodecylborane, trioctadecylborane, trieiscosylborane,tri-triacontylborane, tritetracontylborane, and the like;trialkenylboranes as, for example, trivinylborane, tri-l-butenylborane,tri-Z-octenylhorane, trioctadecenylborane, tri-triacontenylborane, andthe like; alkynylboron compounds as, for example, tri-lhexynylborane,tri-Z-octynylborane, and the like; cycloalkyland cycloalkenylboroncompounds as, for example, tricyclobutylborane, tricyclohexylborane,tricyclooctylborane, tricyclobutenylborane, tricyclohexadienylborane,and the like; arylboron compounds as, for example, triphenylborane,trinaphthylborane, tri (2 phenylethyl)- boraue, tribenzylborane,tritolylborane, and the like; mixed organoboranes as, for example,methyl-diethylborane, octyl-dihexylborane, phenyldioctadecylborane, andthe like; cyclic or polymeric hydrocarbon boron compounds as, forexample, butane-'1,4-bis( l-boracyclopentane) O (CHM-BO pentane-1,5-bis(l-boracyclohexane); l-n butylboracyclohexane; 1-n-butylboracyclopentane;compounds having the moiety l CHa-OHa- GHr-CHzn where n is at least 2;and the like; hydrocarbonboron acids as, for example, 'benzyl boronicacid, ethyl boronic acid, phenyl boronic acid, dioctadecyl boronousacid, and the like, and their corresponding salts of metals,particularly the alkali metals, as for example, sodium, lithium,potassium, and cesium; hydrocarbonboron halides as, for example,dihexylboron chloride, dioctadecylboron fluoride, dioctylboron bromideor iodide, and the like; hydrocarbon borines as, for exampledihexylboron hydride, tetradecyl diborane, and the like; and hydrocarbonboron compounds also containing inorganic and organic acid anions as,for example, dihexylboron sulfate, dihexylboron nitrate, dihexylboronacetate, dihexylboron octadecanoate, and the like. Another type ofcyclic organoboron compound also employable are those illustrated by,for example, trimethyl boroxine (MeB) trihexyl boroxine, trioctadecylboroxine, and the like. The above compounds are presented by way ofillustration and it is not intended to be limited thereto. in general,the hydrocarbon moieties contained in such compounds will have up to andincluding-about 40 carbon atoms. It is to be understood that thehydrocarbon groups can be further substituted to result in branch chainsand isomers thereof as well as being substituted by other functionalgroups which are essentially inert in the reaction or do not defeat theoxidation of the carbon-boron linkages desired. It is preferable,however, to employ the trialkylboranes in which the alkyl groups arepreferably straight chain hydrocarbon groups having up to and includingabout 40 carbon atoms. These reactants are more easily prepared, morestable and economical and result in the greatest practical production ofalcohol or boron ester, as the case may be.

The process of this invention involves a controlled oxidation of thecarbon to boron linkages. For this purpose either oxygen or air isemployed. Thus, the oxygen can be that as commercially available or airitself can be efiectively used. Depending upon the economies to beeffected, oxygen is sometimes preferable since minimum reactor space isnecessary to obtain the requisite amount of oxygen in contact with theorganoboron compound. However, air is generally preferred because of itseconomy. Wet or dry air or oxygen are equally suitable, with wet air oroxygen being preferred.

The process of this invention is conducted in the presence of amines orammonia since, by virtue thereof, it has been found that the oxidationproceeds rapidly and etficiently to effect complete and controlledoxidation of all boron-carbon linkages. -While, in general, any amine isemployable, it is preferable to employ those which are either liquidunder the reaction conditions or dissolve in the reaction mixture.Therefore, in general, the primary, secondary, tertiary, andheterocyclic amines are applicable including those wherein thehydrocarbon portions are aliphatic, cycloaliphatic, or aromatic moietiessuch as the alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl,alkaryl, aralkyl, and the like. Typical examples of the primary aminesinclude methyl amine, ethyl amine, butyl amine, decyl amine, octadecylamine, vinyl amine, hexenyl amine, l-hexynyl amine, cyclohexyl amine,phenyl amine, benzyl amine, tolyl amine, and the like. Typical examplesof the secondary amines include diethyl amine, didecyl amine,dioctadecyl amine, dihexenyl amine, diheptynyl amine, methylcyclohexylamine, dicyclohexyl amine, diphenyl amine, and the like. Typicalexamples of the tertiary amines include trimethyl amine, triethyl amine,tributyl amine, trioctyl amine, tri- Dctadecyl amine, tributenyl amine,myristyl dimethyl amine, .trihexenyl amine, tricyclohexyl amine,tri-hexynyl amine, triphenyl amine, tritolyl amine, dimethylaniline, andthe like. Among the heterocyclic amines are included, for example,pyridine, p-methy-l pyridine, 3- benzyl pyridine, 2-propyl pyridine andthe like. It is to be understood that the hydrocarbon moieties of theaforementioned amines can be further substituted to result in branchchains or further substituted with functional groups which areessentially inert in the reaction. In general, the hydrocarbon moietieswill contain up to and including about 18 carbon atoms although longerchain moieties are employable. It is preferable to employ the tertiaryamines, particularly the trialkyl amines in which the alkyl groups arehydrocarbon containing up to about 10 carbon atoms. The trialkyl aminesare preferred be cause of their greater availability and practical usein the process. 7

While it is not necessary, it is preferable to conduct the reaction inthe presence of water in order that the more useful alcohol products bedirectly obtained in the reaction mixture; Likewise, although notessential, inert diluents can also be incorporated in the reactionsystem as an additional means for controlling the reaction temperatureor to provide greater solubility of the reactants. The only criteria ofsuch diluents are that they be essentially inert to the reaction, thatis not react with the reactants or products. For this purpose theaforementioned amines are employable and the hydrocarbons, particularlythe liquid hydrocarbons having up to about 18 carbon atoms as, forexample, hexane, decane, cyclohexane, toluene, benzene, and the likeincluding mixtures such as mineral oil, gasoline, and the like.

The proportions of the reactants and diluents are not critical and arelimited only by the extent of reaction desired and the reactionconditions. For example, only sufiicient oxygen, either pure or in air,is required to oxidize the carbon to boron linkages. It is preferable toemploy at least enough oxygen to oxidize all of the carbon to boronlinkages. An eilicient way to accomplish this is to maintain a constantpressure of the oxygen or air in the reaction system. While such resultsin the employment of excessive amounts of the oxygen or air, this is notdeleterious since it is readily recoverable and reused as well as beingan economical reactant. The ammonia or amine can be present in minoramounts, e.g. as little as 0.01 mole thereof per mole of carbon to boronlinkages, thus, even such small amounts of this catalytic material havesome efiect on the rate of oxidation and the ability to accomplish theoxidation of the carbon-boron linkages including the so-called lastcarbon to boron linkage. In order to achieve best results, it ispreferable to employ at least one sixth of a mole of the amine orammonia per mole of carbon to boron linkage. There is essentially noupper limit to the amount of the amine or ammonia employed sinceexcessive quantities as, for example, solvent quantities, are readilyrecoverable and reused. The effect of the ammonia or amine is apparentwhether or not the system is acid or basic. In those embodiments whereinwater is employed in the reaction system resulting directly in thealcohol being produced, generally at least enough water is maintained tohydrolyze the ROB moieties to the alcohol. Thus, for practical reasons,at least one mole of water per carbon to boron linkage or (ROB) linkagecontained in the boron reactant is employed with considerable excessalso being applicable but not necessary. In those instances wherein anadditional diluent is employed as, for example, the hydrocarbons, theycan be present in varying amounts but usually only sufficient to providea fluid reaction system with the attendant amount of heat controldesired.

The manipulative operations of the process of this invention are subjectto considerable latitude. In general, however, the hydrocarbon boroncompound and ammonia or amine are admitted to a reactor along with waterand/or hydrocarbon diluent, if so desired, in any order of addition andoxygen or air is bubbled through the reaction mixture and/or pr ssuriz din the y t with heating where necessary to the desired temperature. Theoxidation takes place rapidly and the products and diluents are readilyrecoverable by conventional techniques. 'In those instances whereinwater is employed and the alcohol is formed directly, generally thealcohol is insoluble in the water and can be continuously withdrawn fromthe reaction system. It will be evident that other conventionaltechniques of reaction sequences and systems Will be applicable.

The present invention will be more completely understood from aconsideration of the following examples wherein all parts are by weightunless otherwise indicated.

Example I Employing a reactor equipped with internal agitation, a meansfor introducing and discharging reactants and a means for maintainingpressure, there is added thereto 7 parts of tri-n-hexyl-borane. Then, 1part of triethylarnine is added thereto and the reaction mixturepressurized to 200 p.s.i. of essentially pure and dry oxygen. Reactionimmediately takes place and these conditions are maintained for /2 hourwhile constantly maintaining the aforementioned pressure of oxygen.Then, the temperature is slowly raised to 120 C. and the pressure andtemperature maintained for an additional /2 hour. In this manner,tri-n-hexylborate is produced in high yield which is readily separatedfrom the reaction mixture by distilling off the triethylamine and can beconverted to n-hexyl alcohol by adding water to the tri-n-hexylborate.

Example II The reactor of Example I was again employed. In the reactor,tri-n-hexylborane in trimethylamine was prepared in situ by reacting1.83 parts of trimethylamine borane (Me N-BH with 6.3 parts of l-hexeneat 150 C. for 1 /2 hours. The reaction mixture was then cooled to roomtemperature and 20 parts of a 5 percent sodium hydroxide solution wasadded thereto. The reactor was then pressurized gradually over a 2-hourperiod to 200 p.s.i. of oxygen maintaining room temperature. Then, thereactor was heated to 150 C. with the pressure of oxygen being graduallyincreased to 800 p.s.i. over a period of about 1 /2 hours and theseconditions maintained for 11 hours, at which time the reactor was cooledto room temperature and vented. The reaction mixture was washed into aseparator with water and the hexyl alcohol product was extracted withchloroform and filtered. Analysis showed that 6.3 parts of n-hexylalcohol were obtained representing a yield of 82 /2 percent.

Example III In this run, 5 parts of tri-n-hexylborane were added to thereactor'along with 20 parts of water and 1 part of triethylamine. Thereactor was pressurized at room temperature gradually over a 2-hourperiod to 200 p.s.i. with oxygen. At the end of this period, thetemperature was then raised to C. and the pressure maintained between500 and 800 p.s.i. for an additional 18-hour period. Very little oxygenwas taken up by the reaction during the last 15 hours of reaction whichshowed that the controlled oxidation was essentially complete after 3hours. At the end of this period, the reaction mixture was cooled toroom temperature and vented and the product worked up as in Example II.The yield of n-hexyl alcohol was 83 percent.

When this example is repeated with exception that 20 parts of ammoniaare bubbled into the water in place of the amine, forming ammoniumhydroxide with an excess of ammonia present, similar satisfactoryresults are obtained.

Example IV The procedure of Example III was repeated essentially asdescribed with the exception that after reacting for essentially 1 hourand 20 minutes at room temperature while gradually increasing the oxygenpressure to 200 p.s.i., the reactor was heated to 95 C. and the pressuremaintained at 600 p.s.i. for an additional 11 /2 hours. Analysis byvapor phase chromatography showed a 70 percent yield of n-hexyl alcohol.

In contrast to the above results, when 5 parts of tri-nhexylborane inadmixture with 20 parts of a' 5 percent sodium hydroxide solution wasreacted with oxygen at 400 p.s.i. with the maximum temperature at C.over a period of 13 hours in the absence of any amine, only a 60 percentyield of n-hexyl alcohol was obtained. Likewise, when 13 parts oftri-n-hexylborane was oxidized in the absence of water or amine with themaximum dry oxygen pressure at 500 p.s.i. and the maximum temperature at150 C. over a period of 12 hours, only a 36' percent yield of n-hexylalcohol was obtained after hydrolysis of the boron esters formed. Thus,it is evident that in the latter runs, no more than two of the carbon toboron linkages reacted. Further, these comparison illustrate the markedeffect achieved by the presence of the amine whereby all of the carbonto boron linkages in the starting reactant are oxidized. v p

The following examples will illustrate additional embodiments of thepresent invention.

7 Example V A mixture of organoboranes obtained by reacting diboranewith a mixture of C through C primary olefins is reacted with oxygen inthe presence of parts of triethylamine and 20 parts of water at atemperature of 100 C. with the oxygen pressure maintained at 1000 p.s.i.over a period of hours. At the end of this period, the mixture is cooledto room temperature and an alcohol layer comprising C through C alcoholsis readily separated in high yield.

Example VI When 10 parts of tri-n-octylborane is reacted with oxygen inthe presence of 2 parts of pyridine and 5 parts of water at 150 C. and500 p.s.i. for 4 hours after first reacting the mixture at roomtemperature and 500 psi for 2 hours, n-octyl alcohol is obtained in highyield.

Example VII To an autoclave is added 10 parts of tricyclohexylborane, 10parts of dimethyl aniline and 10 parts of water. Then oxygen ispressurized to 150 p.s.i. into the system at room temperature andtheseconditions maintained for 1% hours with agitation. The reactor isthen heated to 125 C. and the oxygen pressure increased to 750 p.s.i.These conditions are maintained for 8 hours. At the end of this period,the reaction mixture is cooled and the cyclohexanol layer is separated.Cyclohexanol is recovered in high yield.

Similar results are obtained when tricyclopentylborane,tricyclobutylborane, tricycloheptylborane, and tricyclehexenylborane aresubstituted for tricyclohexylborane in the above example.

Example VIII When 5 parts of tri-Z-hexenylborane in 1 part of anilineand 2 parts of water are oxidized employing air at a constant pressureof 1000 p.s.i. at 160 C. for 6 hours, 2- hexenyl alcohol is obtained inhigh yield.

Similar results are obtained when other olefinic boron compounds aresubstituted for tri-2-hexenylborane in the above example as, forexample, tri-l-octenylborane, tri- 3-octadecenylborane,tri-2-dodecenylborane, and the like.

Example IX Phenol is obtained in high yield and purity when 10 parts ofphenyl boronic acid in 4 parts of tri-n-butyl amine and 20 parts ofwater are oxidized at 100 C. and 800 p.s.i. oxygen pressure for 10hours.

Equally satisfactory results are obtained when ethyl boronic acid,propyl boronic acid, diphenyl boronous acid, triphenyl boroxine, and thelike are substituted for phenyl boronic acid in the above example.

Example X Sec-butyl alcohol is obtained in high yield and purity whentri-sec-butyl borane is oxidized with air when in admixture withcyclohexylamine and water at 135 C. and 100 psi. for 18 hours.

Example XI When trioctadecylborane is oxidized with air at 65 C. and1000 p.s.i. in the presence of .10 parts of myristyl dimethyl amine and5 parts of water per part of the borane for hours, octadecyl alcohol isobtained in high yield with essentially all of the carbon to boronlinkages being oxidized.

Example XII When the procedure of Example X is repeated substitutingtriisoamylborane for tri-sec-butylborane and triethyl amine forcyclohexyl amine, isoamyl alcohol is obtained in high yield and purity.

Example XIII S-hexynyl alcohol is produced when tri-S-hexynylborane isreacted with oxygen at 75 C. and 300 p.s.i. in the presence of trimethylamine and water for 7 hours.

Equally satisfactory results are obtained when tri-3- heptynylborane,tripropynylborane, and the like acetylenic boranes are substituted fortri-S-hexynylborane in the above example.

Example XIV When 15 parts of p-tolylboron dichloride are reacted withoxygen in the presence of 10 parts of ethylene diamine and 12 parts ofwater at C. and 500 psi. for 12 hours, p-tolyl alcohol is obtained inhigh yield.

Similar results are obtained when other organoboron halides aresubstituted for p-tolyl boron dichloride in the above example, as forexample, diphenyl boron chloride, dimethyl boron fluoride, phenyl borondibromide, hexyl boron diiodide, and the like. While generally thehydrocarbon boron halides tend to hydrolyze in water systems and thusare less preferred, the resulting product of the hydrolysis is thecorresponding hydrocarbon boron acid which as indicated previously iswell suited to the process of this invention.

Example XV When triethylboroxine (EtBO) is reacted with oxygen in thepresence of cyclohexylamine and water at 100 C. and 200 p.s.i. for 10hours, ethyl alcohol is obtained in high yield.

Similar results are obtained when other boroxines are substituted in theabove example, as for example, trimethylboroxine, trioctylboroxine,trioctadecylboroxine, and the like.

Example XVI When Example III is repeated substituting other amines as,for example, ethylamine, diamyl amine, vinyl amine, dicyclohexyl amine,benzyl amine, diphenyl amine, and the like for triethylamine in varyingproportions, similar results are obtained.

Example X VII When Example IH is repeated substituting butane-1,4- bis-(l-boracyclopentane) for the tri-n-hexylborane, tetramethylene glycol isobtained in high yield.

Similar results are obtained when other cyclic or polymeric hydrocarbonboron compounds are substituted in the above example as, for instance,pentane-l,5-bis-( lboracyclohexane) to produce 1,5-pentanediol,1-n-butylboracyclopentane to produce a mixture of n-butyl alcohol and1,4-butanediol which canbe separated, if desired, the reaction productof diborane with acetylene in a molar ratio of 1 to 3 respectively toproduce ethylene glycol, and the like. a

The above examples are presented by way of illustration and theinvention is not to be limited thereto. It is evident that similarresults are readily obtainable when substituting other organoboroncompounds, amines, and conditions described hereinbefore.

The temperature at which the reaction is conducted is subject toconsiderable latitude, the only limitation being that it is generallybelow the degradation temperature of the organoboron reactant,Generally, however, the reaction is conducted at a temperature betweenabout 0 to C. Temperatures much above 150 C. are not required and areless preferable since some degradation begins to take place. Likewise,temperatures much below 0 C. are not employed since at these conditions,the reaction proceeds more slowly. As indicated by some of the aboveexamples, it is frequently desirable to employ a two-step heatingoperation. This is particularly the case where a trialkylboron is theorganoboron compound being oxidized. For example, in such instances, itis usually advantageous to conduct the oxidation at temperatures betweenabout to 40 C. until essentially the first two boron to carbon linkageshave been oxidized and then to conduct the remainder of the oxidation attemperatures between about 40 to 150 C. It has been found that theseconditions are admirably suited when reacting the trihydrocarbon boroncompounds since better control as well as complete controlled oxidationis obtained.

Similarly, while the reaction can be conducted at atmospheric pressure,pressures above atmospheric are preferably employed for more eflicientoperation. The maximum pressure used is limited primarily only by thepracticalities involved and for this reason generally the pressure is upto about 5000 p.s.i. More eflicient operation is obtained when theoxygen or air pressure is not higher than about 1000 p.s.i. The reactiontime employed is dependent somewhat upon the reactants involved and thereaction conditions but can also be widely varied. Ordinarily, completeoxidation is obtained at reaction times up to about 20 hours and longerreaction times are not required or desirable. Generally reaction timesup to 10 hours are suitable and preferred.

In those embodiments wherein the reaction is conducted in the absence ofwater, the boron ester which is produced is generally soluble in thereaction mixture but is readily recoverable by simple separationtechniques. Whether it is soluble or insolube, or in those instanceswherein Water is employed to result in the direct formation of analcohol, fractional distillation techniques can be employed to effectefiicient separation. Generally, however, in those instances where thealcohol that is formed is of a long chain length, that is, above aboutcarbon atoms, it will be insoluble in the reaction mixture and can berecovered by simple decantation. In those instances wherein the alcoholproduced is soluble in the reaction mixture, it can also be extractedwith suitable solvents therefor which are insoluble in the reactionmixture or a presaturated solution of the alcohol, water and amine canbe employed which will automatically result in a phase separation of thealcohol which is produced. Similar tech niques. can be used where theester is produced rather than the alcohol. Salting out techniques arealso available as, for example, adding alkali metal carbonates to thereaction mixture. -The alcohol or ester likewise is generally easilyseparable from the amine catalyst. In any event, the amine can be washedout with water or acid or it can be distilled from the alcohol or ester.When required, the amine is generally distilled under conditions whichare not destructive of the amine. Other methods of recovery of theprincipal product will be evident to those skilled in the art. It is tobe understood that the reaction mixture can be employed as obtained, ifdesired, without any separation.

The boron esters and alcohols produced according to the respectiveembodiments of this invention are of considerable and well knownutility. For example, the esters, such as triethylborate, can be reactedwith sodium hydride to produce sodium borohydride or they can beemployed as additives to motor fuels. They likewise can be readilyconverted to the corresponding alcohols by simple hydrolysis techniques.In the embodiments of the invention wherein the alcohol is directlyproduced, the alcohols are of particular utility as intermediates forthe formation of various detergents. For example, any of the productsproduced according to the Examples II through XVII, particularly thosewith 6 carbon atoms or more, can be reacted with sulfuric acid to formthe corresponding sulfate esters from which the corresponding alkalimetal salts are obtainable by conventional techniques. The resultingsulfates are efiicient detergents and cleansing agents of known utility.Many other diverse uses of alcohols are well known in the art. I

Having thus described the process of this invention, it is not intendedthat it be limited except as set forth in the following claims.

We claim:

1. The process for the manufacture of a boron ester which comprisesoxidizing a hydrocarbon boron compound having at least one carbon toboron linkage with oxygen in the presence of a nitrogen-containingcompound selected from the group consisting of a hydrocarbon amine andammonia.

2. The process of claim 1 further characterized in that the reaction isconducted at a temperature between 0 to C. in the further presence ofwater.

3. A process for the manufacture of alkanols which comprises reacting atrialkylborane with oxygen at a temperature between about 0 to 150 C.and a pressure between about atmospheric and 5000 p.s.i. in the presenceof a hydrocarbon amine and Water.

4. A process for the manufacture of n-hexyl alcohol which comprisesreacting tri-n-hexylborane with oxygen at a temperature between about 0to 150 C. and a pressure between about atmospheric and 1000 p.s.i. inthe presence of a trihydrocarbon amine and water.

5. The process of claim 4 further characterized in that said amine ispresent in amount of at least 0.01 mole per mole of the carbon to boronlinkages in said tri-n-hexylborane and said water is present in amountat least sufficient to hydrolyze the oxidized product to thecorresponding alcohol.

6. The process of claim 5 wherein said amine is triethylamine.

7. The process of claim 3 wherein said hydrocarbon amine is atrialkylamine.

8. The process of claim 1 further characterized in that said hydrocarbonboron compound is a trialkylborane, in that the reaction is conducted ata temperature between about 0 to 150 C. and at a pressure aboveatmospheric but below about 1000 p.s.i., and in that saidnitrogencontaining compound is a trialkylarnine.

9. The process of claim 8 further characterized in that it is conductedin the further presence of water.

References Cited in the file of this patent UNITED STATES PATENTS2,542,746 Banus et al Feb. 20, 1951 2,862,951 Stafiej Dec. 2, 19582,875,236 Levens et al Feb. 24, 1959

1. THE PROCESS FOR THE MANFACTURE OF A BORON ESTER WHICH COMPRISESOXIDIZING A HYDROCARBON BORON COMPOUND HAVING AT LEAST ONE CARBON TOBORON LINKAGE WITH OXYGEN IN THE PRESENCE OF A NITROGEN-CONTAININGCOMPOUND SELECTED FROM THE GROUP CONSISTING OF A HYDROCARBON AMINE ANDAMMONIA.